Modular jack receptacle connectors mounted to printed circuit boards (PC boards) are well known in the telecommunications industry. These connectors are typically used for electrical connection between two electrical communication devices. In order to ensure that a proper connection has been made and therefore that a link is created between the electrical communication devices, indicators such as light emitting diodes (LEDs) are often incorporated into circuits on the PC board to indicate that power is on or to indicate that an error has occurred in the transmission of signals. These LEDs were initially mounted on PC boards; however, in an effort to miniaturize PC boards and save PC board real estate, LED indicators have been integrated into the connectors.
An example of such a connector is disclosed in U.S. Pat. No. 4,978,317 to Porcrass which teaches a connector for receiving a plug which has a visual indicator positioned within the front wall of the electrical connector housing. Incorporation of the indicator into the connector eliminates the need for a separate location on the printed circuit board for mounting of such an indicator. The LED indicator is situated in a recess of the electrical connector with its electrical leads extending through the housing to connect to the printed circuit board. The indicator is secured in the housing using appropriate adhesive or mechanical means. LEDs may also be molded into the electrical connector during the manufacturing process.
Another approach to the above-described space problem is to incorporate a light guide or light pipe in the housing of the jack, which light guide extends from the front face of the housing to a bottom area of the housing generally adjacent an LED mounted on the PCB. Such a light guide is typically of a light transmitting plastic which has a light entry surface, a light reflecting surface for directing the light forward, and a light output surface at the front face of the housing. Further examples of prior art jacks and light pipes are disclosed in U.S. Pat. No. 5,876,239 to Scott F. Morin et al., U.S. Pat. No. 5,915,993 to Yakov Belopolsky et al., U.S. Pat. No. 5,613,873 to Joseph W. Bell, Jr., U.S. Pat. No. 5,741,152 to Kamal S. Boutros and U.S. Pat. No. 5,790,041 to Sherman Lee, which are incorporated herein by reference.
Space is a critical aspect in state-of-the-art connectors of the type considered herein. The space available for the light guide within the housing is highly limited, as is the vertical height of the light-viewing window in the front wall of the connector. This becomes a particular problem where an LED on the PC board contains a pair of light-emitting chips spaced axially in the rear-to-front direction. The limited height available for the light pipe may result in inadequate light transmission from the LED to the front window. One factor causing space problems is the forty-five degree inclination of the rear reflecting surface in a basic rectangular block prior art light pipe. With this shape the maximum cross-section for light transmission is established. If the length of the light emission area of the LED is relatively long, particularly with the dual light emitting chips on a single LED, some light from one or both of the light chips will be lost and thus not communicated to the front window. A light guide with a greater height would solve this problem; however, such additional height is usually not available. The present invention provides a novel and effective solution as explained below.
This invention is a new modular jack having a novel light pipe incorporated therein and this jack in combination with the PC board. The invention further includes the new light pipe alone for use in other modular jacks and a new method of transmitting light from an LED to a light-viewing window in the jack. A first objective herein is to transmit light from an LED on the printed circuit board to the front face of a modular jack housing. It is desired to reduce loss as light is transmitted from the light source to the destination which is typically a window in the jack. A further objective is to overcome the space problem that now exists when using modular jacks on printed circuit boards. Space is critically limited on the PC boards, on the face of the jacks and in the height dimension within the connector perpendicular to the face of the PC board. Where a light pipe is used within a jack, manufacturing tolerances require allowance of specific clearance space to separate the LED from the light pipe. This consumes still further space of the PCB and jack assembly. This invention thus seeks to integrate in a new way, light indicator technology, modular connectors and PC boards to reduce space use, minimize light loss, and enhance light transmission.
The above objectives have been achieved in the present invention by a novel and unusual light guide or light pipe whose configuration allows enhanced light transmission in a reduced size. In a particular embodiment the new light guide allows light from an elongated LED to be captured and directed to a window in the front face of the jack. This is achieved in part by a series of notches or channels extending transversely across the top and/or bottom walls of the light pipe, which create a plurality of additional light reflection surfaces. Light from the LED is directed to these various reflection surfaces and thence via various paths to the illuminated window to indicate on/off conditions of respective circuits. These notches allow more light from a greater source area to be captured with a smaller light pipe, this light then being directed to the front indicator window on the modular jack. These new notches or surface channels and resulting new reflection surfaces reduce light loss and help to overcome space constraints created where a modular connector is coupled to a PC board.
In one preferred embodiment of this invention one or two notches are established in the top wall of the light pipe to create respectively one or two primary light reflection surfaces. A notch in this configuration means a channel or groove or beveled surface extending transversely across the light pipe between its sides. Each notch results in a surface defining an acute angle with respect to the longitudinal axis of the light pipe. Light directed onto such reflection surfaces will be reflected generally in the axial direction to the front end of the pipe where it will be visible through the window in the jack""s front wall or through the window in the front shield at the front of the jack.
In another embodiment of this new invention it is possible to use a light pipe having height perpendicular to the plane of the LED that is less than the length of the LED in the axial direction of the light pipe, and to still capture the available emitted light with a minimum of loss, and to direct or focus the captured light to the window which also has height less than the axial length of the LED.